Questions surrounding Internet Protocol version 6 (IPv6) have been debated for the past decade, beginning with when and why to deploy. The network address space problem on the Internet, which IPv6 is expected to solve, also has been disquieting for organisations planning ahead for their future network growth.

Common networked applications and communications have not yet required IPv6. So far, networks have been stable with IPv4 and the amount of allotted address space. IPv4, however, offers a strict ceiling of 4.3 billion addresses. Each device connecting to the Internet requires a unique address. Work-through tactics such as network address translation, though, have effectively extended the life of IPv4. The date for true IPv4 address scarcity, hindering a network's growth potential, has been predicted to be some time in 2010.

While IPv6 offers almost limitless addresses, in the trillions, among other benefits such as simplifying networks with the auto-configuration of mobile devices, there are a few issues to be aware of when planning for IPv6. First, no single business case for IPv6 adoption is available to apply to all organisations. One constant is that the best step is to gain the latest intelligence and plan comprehensively.

Since 2000, there have been four primary objections to what many call IPv6 hype:

• Network equipment, switches and devices did not yet properly support it;

• IPv6 would require many "bumps and bruises" to have installed;

• IPv6 had no suitable applications; and

• IPv4 remained useful with plenty of time and IP address space left.

Various efforts by the standards community, vendors and the user community have helped allay many IPv6 fears. IPv6, now built into some Ethernet switches, has undergone countless tests within academic, military and government environments over the past four years. These tests have focused on conformance, interoperability, functionality and performance.

The Internet Engineering Task Force has spent more than 10 years designing IPv6. In addition, the IPv6 Forum, a worldwide collection of vendors, ISPs, researchers and educational institutions, was assembled to promote its adoption. In conjunction with this, the University of New Hampshire InterOperability Laboratory has been conducting tests on vendor gear to ensure it successfully passes both interoperability and conformance tests. The net result of testing has demonstrated the reliability and interoperability of IPv6 solutions.

Ethernet switches and operating systems are also supporting IPv6 and IPv4 concurrently, providing translation of both technologies and offering a smooth transition for users. Applications are also getting up to speed, with the most visibility coming with the Windows Vista platform and its out-of-the box support of both IPv4 and IPv6. Windows XP and Windows Server 2003 were the first to implement IPv6 in dual-stack architecture, used as building blocks to enable IPv6 within Vista. Apple's Mac OSX and Linux also come with IPv6 support, giving a wider menu of software options to prospective organisations.

While some common Internet applications already work with IPv6, other software applications may need updates or customisation. The easiest way to port an IPv4 application is to substitute the old IPv4 API references with the new IPv6 APIs using one-to-one mapping. This way, the application will be IPv6-only. While the process may temporarily inconvenience users, it will ensure a smooth transition. As applications get ported to support both IPv4 and IPv6, existing IPv4-only applications can be phased out.

As IPv6 is expected to gradually replace IPv4, the two will need to coexist during the transition. Advanced networks can run both IPv4 and IPv6 concurrently throughout the migration. This means networks can equally support features like quality of service, multicasting and routing.

Many routing and interworking protocols have been established to accommodate the transition to IPv6, including dual-stack, tunnelling and translation standards. With dual-stack, networks receive full support for both IPv4 and IPv6 in routers and hosts. With tunnelling, encapsulation of IPv6 within IPv4 is used to traverse IPv4 networks. Finally, with translation, each protocol allows IPv6-only devices to communicate with IPv4-only devices.

When IPv6 is ready to go, the security infrastructure should be reviewed to ensure access control lists in the network and the firewall cover IPv6 transport traffic. IPv6 can introduce both known and unknown security considerations; therefore, make sure the security measures are updated to address IPv6 concerns.

- Aaron Condon is acting country manager for Extreme Networks Australia and New Zealand.